Characterization of chromosomally encoded penicillinases in clinical isolates of Klebsiella pneumoniae.

Four Klebsiella pneumoniae strains, isolated in two geographically distant French hospitals, were found to produce constitutive beta-lactamases with an unusual isoelectric point for this species (8.1). The four enzymes were chromosomally encoded and related to the Ambler's class A plasmid-mediated SHV-type enzymes.

Does high level production of SHV-type penicillinase confer resistance to ceftazidime in Enterobacteriaceae?

We report the isolation of a clinical isolate of Klebsiella pneumoniae that showed resistance to ceftazidime (MIC: 8 micrograms/ml), susceptibility to aztreonam (MIC: 2 micrograms/ml) and cefotaxime (MIC: 0.015 micrograms/ml). A synergistic effect between clavulanic acid and ceftazidime or aztreonam against this strain was also observed.

[Identification of a new penicillinase in a Klebsiella pneumoniae strain of which a mutant also produces an esterase hydrolyzing cephalothin and cefotaxime].

Klebsiella pneumoniae strain L 164 produces a penicillinase whose isoelectric point is 8.1, an unusual figure for this bacterial species. This strain exhibits resistance to conventional penicillins and a synergistic effect is seen with clavulanic acid.

Chromosomally-mediated beta-lactamases produced by Levinea amalonatica with activity against methoxyimino-cephalosporins.

Levinea amalonatica strain A2370 was isolated from the blood culture of a patient hospitalized in Charles Nicolle hospital (Tunis) during July 1986 and had decreased susceptibility to cefotaxime. Isoelectric focusing of crude extracts from this strain demonstrated three bands of beta-lactamase activity which focused at pH 5.4, 5.